An inkjet printing method of discharging ink to print an image is widely used for printers, copying machines, facsimile apparatuses, and the like because of small noise, low running cost, easy downsizing of an apparatus, and facilitation of color image printing.
An example of printheads used for the inkjet printing method is a multi-nozzle inkjet head having a plurality of nozzles.
In this printhead, electrothermal energy transducers (heaters) are arranged together with wiring lines at equal intervals on, e.g., a silicon substrate, resin layers are stacked between the respective electrothermal energy transducers to form partitions, and a liquid channel formation plate is bonded to each partition to form an orifice.
FIG. 10 is a circuit diagram showing a conventional driving circuit for driving a printhead.
As shown in FIG. 10, n (n is a positive integer) AND gates 2-1, 2-2, 2-3, 2-4, . . . , 2-n are arranged for n (n is a positive integer) electrothermal energy transducers 1-1, 1-2, 1-3, 1-4, . . . , 1-n, respectively. Each of the AND gates 2-1, 2-2, 2-3, 2-4, . . . , 2-n receives a block selection signal (HE0, HE1, BE0 (BE0_0, BE0_1)) corresponding to sequential block driving of the electrothermal energy transducers 1, a printing data signal (IDATA), and an energization time setting signal (HC).
Printing data (IDATA) equal in the number of bits to the electrothermal energy transducers 1-1, 1-2, 1-3, 1-4, . . . , 1-n are sequentially transferred to a shift register 4 of a printing data supply unit 40 in synchronization with a printing data transfer clock (DCLK). After all the data are input, they are read in a latch circuit 3 in response to input of a latch signal (DLAT).
Block selection signals (HE0, HE1, BE0 (BEO_0, BE0_1)) corresponding to sequential block driving of the electrothermal energy transducers 1-1, 1-2, 1-3, 1-4, . . . , 1-n are input. Only while the energization time setting signal (HC) is ON, the printing data (IDATA) are selectively supplied to the electrothermal energy transducers 1-1, 1-2, 1-3, 1-4, . . . , 1-n. Then, ink is discharged from orifices by the action of bubbles generated by thermal energy.
However, the conventional printhead driving circuit shown in FIG. 10 requires many signal lines (EI, IDATA-BK, IDATA-C, IDATA-M, IDATA-Y, DCLK, DLAT, HE0, HE1, BE0 (BE0_0, BE0_1), HC-BK, HC-C, HC-M, and HC-Y) extending from a host head control circuit to BK, C, M, and Y head driving circuits arranged for respective, black, cyan, magenta, and yellow inks, as shown in FIG. 11, in performing sequential/divisional block driving because the driving blocks of the printhead are determined by a plurality of block selection signals (HE0, HE1, BE0 (BE0_0, BE0_1). If the number of blocks subjected to sequential/divisional block driving increases, the number of signal lines extending from the host head control circuit must be increased, resulting in a complicated circuit arrangement.